1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the invention relates to visualization devices and methods for facilitating cardiac surgical procedures, such as repair of the mitral or tricuspid valve for treating mitral or tricuspid regurgitation.
In recent years, many advances have been made to reduce the invasiveness of cardiac surgery. In an attempt to avoid open, stopped-heart procedures, which may be accompanied by high patient morbidity and mortality, many devices and methods have been developed for operating on a heart through smaller incisions, operating on a beating heart, and even performing cardiac procedures via transvascular access. Different types of cardiac procedures, such as cardiac ablation techniques for treating atrial fibrillation, stenting procedures for atherosclerosis, and valve repair procedures for treating conditions such as mitral regurgitation have experienced significant technological advances. In implementing many, if not all, transvascular, minimally invasive and other cardiac surgery techniques, visualization of the heart, the surgical field, surrounding structures, and the like is essential. At the same time, visualization is often difficult, due to the rapid movement of a beating heart as well as the large quantities of pumping blood in an intracardiac surgical field.
One type of cardiac surgery which may benefit from less invasive techniques is heart valve repair. Traditional treatment of heart valve stenosis or regurgitation, such as mitral or tricuspid regurgitation, typically involves an open-heart surgical procedure to replace or repair the valve. Valve repair procedures typically involve annuloplasty, a set of techniques designed to restore the valve annulus shape and strengthen the annulus. Conventional annuloplasty surgery generally requires a large incision into the thorax of the patient (a thoracotomy), and sometimes a median sternotomy (cutting through the middle of the sternum). These open heart, open chest procedures routinely involve placing the patient on a cardiopulmonary bypass machine for sustained periods so that the patient's heart and lungs can be artificially stopped during the procedure. Finally, valve repair and replacement procedures are typically technically challenging and require a relatively large incision through the wall of the heart to access the valve.
Due to the highly invasive nature of open heart valve repair or replacement, many patients, such as elderly patients, patients having recently undergone other surgical procedures, patients with comorbid medical conditions, children, late-stage heart failure patients, and the like, are often considered too high-risk to undergo heart valve surgery and are relegated to progressive deterioration and cardiac enlargement. Often, such patients have no feasible alternative treatments for their heart valve conditions.
To obviate this situation, a number of devices and methods for repairing a mitral valve to treat mitral regurgitation in a less invasive manner have been developed. Some devices provide for heart valve repair through minimally invasive incisions or intravascularly, while others improve upon open heart surgical procedures on beating hearts, stopped hearts or both. For example, several improved devices and methods for heart valve repair are described in one or more patent applications filed by the inventors of the present invention and assigned to the assignee of the present invention. For further description of such devices and methods, reference may be made to U.S. patent application Ser. No. 10/461043 , filed on Jun. 13, 2003, which is hereby incorporated fully by reference.
As mentioned above, one of the main challenges in performing minimally invasive surgery on a heart, heart valve, or any other structure is obtaining adequate visualization of the structure and the surgical field. Visualizing a cardiac valve annulus in a beating heart procedure is especially challenging due to rapid movement of the annulus and the heart, the small size of the annulus, and the blood-filled surgical field. Current visualization of minimally invasive cardiac procedures is typically accomplished via transesophageal echocardiogram (TEE). Although this technique works relatively well for some cardiac procedures, it does not provide as clear a picture of the surgical site as would direct visualization. Thus, TEE may not be sufficient for visualizing a minimally invasive procedure within the heart, especially a beating heart procedure to repair a valve annulus.
To obtain direct visualization within the heart, any suitable endoscopic device may be introduced into the heart, such as a conventional endoscope or ultrasonic probe. One problem encountered with such devices, however, is that their ability to provide visualization is often severely reduced by the presence of blood in the heart that surrounds the optic element of the visualization device. A number of devices have been described to combat this problem. For example, U.S. Pat. No. 6,346,074, issued to Roth on Feb. 12, 2002, describes an endoscope having a distal balloon over its end. Such devices still have certain shortcomings, however. For example, balloon-covered endoscope devices are typically introduced into the surgical site through a sheath or introducer device separately from any of the instruments used to perform the cardiac procedure. Thus, the visualization device must typically be manipulated apart from the surgical instruments, and the optical element of the device may often be positioned significantly apart from the working ends of the instruments and the surgical site. In other balloon endoscope devices, the endoscope must be advanced to the surgical site to visualize the site and then removed to allow a surgical instrument to be advanced through the same sheath to perform the procedure. Obviously, such a technique may require numerous, awkward switch-outs of endoscope and surgical instrument and will not result in direct, real-time visualization of the procedure.
Many minimally invasive or “less invasive” surgical procedures other than heart valve repair would also benefit from improved visualization. For example, improved visualization could facilitate other cardiac procedures, such as accessing the coronary sinus for placement of an implantable device or for performing a procedure, placing pacemaker leads in one or more areas of the heart, ablation procedures such as ablation around the pulmonary veins to treat atrial fibrillation, atrial-septal defect repair procedures, and the like. Improved visualization could also be used to enhance non-cardiac procedures such cinching or otherwise treating a bladder, stomach, gastroesophageal junction, vascular structure, gall bladder or the like.
Therefore, it would be beneficial to have improved visualization devices and methods for use in transvascular, minimally invasive and other “less invasive” surgical procedures, such as heart valve repair and other cardiac procedures. Devices and methods for providing such visualization would ideally be minimally invasive and would enhance a physician's ability to locate, visualize and repair a valve annulus, atrial-septal defect, or other cardiac structure accurately and efficiently. Ideally, visualization of the surgical site would be as direct as possible, with an optic element of the visualization device being positioned close to the site. Also ideally, the visualization device would provide visualization at the same time that the physician was performing the procedure and further provide or facilitate access for surgical and/or diagnostic instruments to operate in the visualized field. At least some of these objectives will be met by the present invention.
2. Description of the Background Art
U.S. Pat. No. 6,346,074 describes an endoscope having a balloon over its distal end for use in intracardiac surgery. Patent publications related to mitral valve repair include WO01/26586; US2002/0163784A12; US2002/0156526; US2002/0042621; 2002/0087169; US2001/0005787; US2001/0014800; US2002/0013621; US2002/0029080; US2002/0035361; US2002/0042621; US2002/0095167; and US2003/0074012. U.S. patents related to mitral valve repair include U.S. Pat. Nos. 4,014,492; 4,042,979; 4,043,504; 4,055,861; 4,700,250; 5,366,479; 5,450,860; 5,571,215; 5,674,279; 5,709,695; 5,752,518; 5,848,969;5,860,992; 5,904,651; 5,961,539; 5,972,004; 6,165,183; 6,197,017; 6,250,308; 6,260,552; 6,283,993; 6,269,819; 6,312,447; 6,332,893; and 6,524,338. Publications of interest include De Simone et al. (1993) Am. J. Cardiol. 73:721-722 and Downing et al. (2001) Heart Surgery Forum, Abstract 7025.